Teuchert , D. (Corresponding author)FZJ*

2002
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Report No.: Juel-3964

Abstract: A Computer program system has been developed which allows the generation of highly resolved wind fields in the partially wooded area of the Research Center Jülich. The System uses continuous flow measurements as input, which a.re conducted by an 120 meters high observation tower. The flow module of the system is based upon a diagnostic flow model. A preprocessing module provides the remaining System wich configuration parameters and refined measurement data . Another module provides graphical representation of the results. The System has been developed for operational application of flow computations . Due to the extensively forested surface inside the model area, a parameterisation of the flow through a canopy layer is implemented into the flow model, in order to simulate the flow inside the micro structure of the forest . Different approaches with modified complexity are studied . They are tested and compared with long term measurement data from inside the forest . The measurements enclose vertical profiles of the horizontal wind velocity and direction, and of the radiation balance. The latter ones are used for the identification of the time and intensity of vegetation change. By this way the phases of leaf changing are registered and included into the flow model. Furthermore, the profiles of the drag coefficient (CD), the leaf area density (LAD), and the cumulative leaf area index (LAI) are measured . They are used to calculate the canopy-flow-index (CFI) as a function of height and time which is required in the flow model. The CFI can also be calculate using measured wind profiles from inside the forest, as the two quantities depend an each other. This approach is implemented into the model. The Code system achieves fast calculation of the actual wind flow conditions in the model area, including the canopy flow through the wooded regions . The good agreement between measurements and modelled wind fields during the dominate weather conditions and technical reliability of the Code justify the application of the system in the framework of preventive catastrophe protection at the Research Center in Jülich.

Keyword(s): wind measurement ; flow measurement ; wood ; modeling ; environmental model

1. Abteilung Sicherheit und Strahlenschutz (S)